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Effect of catalyst layer mesoscopic pore-morphology on cold start process of PEM fuel cells

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Frontiers in Energy 2021年第2期15卷 460-472页

作者： Ahmed Mohmed DAFALLA fangming jiang Laboratory of Advanced Energy Systems Guangdong Key Laboratory of New and Renewable Energy Research and DevelopmentCAS Key Laboratory of Renewable EnergyGuangzhou Institute of Energy ConversionChinese Academy of Sciences(CAS)Guangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China

Water transport is of paramount importance to the cold start of proton exchange membrane fuel cells(PEMFCs).Analysis of water transport in cathode catalyst layer(CCL)during cold start reveals the distinct characteristics from the normal temperature *** work studies the effect of CCL mesoscopic pore-morphology on PEMFC cold *** CCL mesoscale morphology is characterized by two tortuosity factors of the ionomer network and pore structure,*** simulation results demonstrate that the mesoscale morphology of CCL has a significant influence on the performance of PEMFC cold *** was found that cold-starting of a cell with a CCL of less tortuous mesoscale morphology can succeed,whereas starting up a cell with a CCL of more tortuous mesoscale morphology may *** CCL of less tortuous pore structure reduces the water back diffusion resistance from the CCL to proton exchange membrane(PEM),thus enhancing the water storage in PEM,while reducing the tortuosity in ionomer network of CCL is found to enhance the water transport in and the water removal from *** the sake of better cold start performance,novel preparation methods,which can create catalyst layers of larger size primary pores and less tortuous pore structure and ionomer network,are desirable.

关键词： cold start energy conversion fuel cells mesoscale morphology tortuosity water management

Simulated annealing reconstruction and characterization of a LiCoO＿2 Lithium-ion battery cathode

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Chinese Science Bulletin 2013年第36期58卷 4692-4695页

作者： WU Wei jiang fangming Laboratory of Advanced Energy Systems Key Laboratory of Renewable Energy and Gas Hydrate Guangzhou Institute of Energy ConversionChinese Academy of Sciences

We reconstruct the three-dimensional microstructure of a cathode from a commercial LiCoO2Lithium-ion battery with an adapted simulated annealing *** real size distribution curve of LiCoO2particles is applied to regulate the reconstruction *** discretizing a 40 m 40 m 40 m cathode volume with 8000000 numerical cubes,the cathode involving three individual phases:(1)LiCoO2as active material,(2)pores or electrolyte,and(3)additives(polyvinylidene fluoride+carbon black)is *** of the reconstructed cathode gives important structural and transport properties including volume-specific surface area between phases,tortuosity and geometrical connectivity of individual phase.

关键词：模拟退火方法锂离子电池钴酸锂阴极三维微结构表征聚偏氟乙烯分布曲线

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具有泡沫金属流场的燃料电池研究进展

新能源进展 2024年第1期12卷 24-34页

作者：艾贤魏魏琳郭剑车帅蒋方明沈阳化工大学机械与动力工程学院沈阳110142 中国科学院广州能源研究所广州510640 中国科学院可再生能源重点实验室广州510640

泡沫金属是一种具有高孔隙率、高电导率、良好传热性和重量较轻等优点的新型多功能材料,在质子交换膜燃料电池(PEMFC)中嵌入泡沫金属作为流场的应用受到越来越多的关注。重点综述PEMFC流场的研究进展,探讨泡沫金属结构参数、流场设计和... 详细信息

泡沫金属是一种具有高孔隙率、高电导率、良好传热性和重量较轻等优点的新型多功能材料,在质子交换膜燃料电池(PEMFC)中嵌入泡沫金属作为流场的应用受到越来越多的关注。重点综述PEMFC流场的研究进展,探讨泡沫金属结构参数、流场设计和环境因素等对功率密度、气体分布、压降和水热管理等性能的影响。进一步讨论泡沫金属流场在PEMFC应用中所面临的腐蚀和水淹问题,以及具备耐腐蚀涂层泡沫金属的研究进展,为PEMFC泡沫金属流场的发展和优化提供有益的启示,以期推进泡沫金属在PEMFC中的应用。

关键词：泡沫金属质子交换膜燃料电池流场设计腐蚀水热管理

A Lightweight Compact Lithium-Ion Battery Thermal Management System Integratable Directly with EV Air Conditioning Systems

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Journal of Thermal Science 2022年第6期31卷 2363-2373页

作者： LIN Bichao CEN Jiwen jiang fangming Laboratory of Advanced Energy Systems Guangzhou Institute of Energy ConversionChinese Academy of SciencesGuangzhou510640China CAS Key Laboratory of Renewable Energy Guangzhou 510640China Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Guangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China

This paper discusses an improved thermal management system to ameliorate the performance of lithium-ion battery storage systems for electric vehicles(EVs) applications. A compact and lightweight cold plate is designed and fabricated to fit 18650-type lithium-ion batteries, using aluminum-finned copper tubes. A dynamic temperature PID(proportional, integral, differential) control algorithm for electronic expansion valves is developed to study using EV air conditioning refrigerant, R134a, to control battery modules’ temperature with this compact and lightweight thermal management system. The experimental results show that the proposed battery thermal management system can effectively control the battery module’s temperature. In addition, during 1C discharge, when the PID temperature algorithm control scheme is used, the maximum temperature difference across the battery module peaks at less than 4℃, and the maximum temperature within the battery module is less than 36℃.

关键词： electric vehicles air conditioning system battery thermal management finned tube two-phase flow

A novel flow-resistor network model for characterizing enhanced geothermal system heat reservoir

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Frontiers in Energy 2019年第1期13卷 99-106页

作者： Jian GUO Wenjiong CAO Yiwei WANG fangming jiang Laboratory of Advanced Energy Systems of CAS Key Laboratory of Renewable Energy and Guangdong Key Laboratory of New and Renewable Energy Research and DevelopmentGuangzhou Institute of Energy Conversion.Chinese Academy of Sciences(CAS)Guangzhou 510640China

The fracture characteristics of a heat reservoir are of critical importance to enhanced geothennal systems,which can be investigated by theoretical *** paper presents the development of a novel *** network model to describe the hydraulic processes in heat *** fractures in the reservoir are simplified by using flow resistors and the typically complicated fracture network of the heat reservoir is converted into a flowresistor network with a reasonably simple *** heat reservoirs with various fracture configurations,the corresponding flow-resistor networks are identical in terms of framework though the networks may have difftrent section numbers and the flow resistors may have different *** this paper,numerous cases of different section numbers and resistor values are calculated and the results indicate that the total number of flow resistances between the injection and production wells is primarily determined by the number of fractures in the *** is also observed that a linear dependence of the total flow resistance on the number of fractures and the relation is obtained by the best fit of the calculation ***,it perfbmis a case study dealing with the Soultz enhanced geothermal system(EGS).In addition,the fracture numbers underneath specific well systems are *** results provide in sight on the tortuosity of the flow path betwee n different wells.

关键词： enhanced geothennal systems flow-resistor network model fracture characteristics heat reservoir

Numerical reconstruction of microstructure of graphite anode of lithium-ion battery

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Science Bulletin 2016年第8期61卷 656-664页

作者： Shaoyang He Jianbang Zeng Bereket Tsegai Habte fangming jiang Laboratory of Advanced Energy Systems CAS Key Laboratory of Renewable Energy Guangzhou Institute of Energy Conversion Chinese Academy of Sciences (CAS)Guangzhou 510640 China University of Chinese Academy of Sciences Beijing 100049China

Due to the presence of graphite flake cascades, the real graphite anode of Li-ion battery shows non-iso- tropic characteristic. The present work developed an ellipsoid-based simulated annealing method and numeri- cally reconstructed the three-dimensional microstructure of a graphite anode. The reconstructed anode is a composite of three clearly distinguished phases： pore （or electrolyte）, graphite, and solid additives, well representing the non- isotropic heterogeneous characteristic of real graphite anode. Characterization analysis of the reconstructed electrode gives information such as the connectivity of individual phase, the specific interracial area between solid and pore phase, and the pore size distribution. The effects of the ellipsoid size on the structural characteristics of graphite anode were particularly studied. As the size of the ellipsoidal particle slightly increases, the average pore diameter increases and as a result the specific interfacial area between the solid and pore phase in the reconstructed area decreases; compared with the equatorial radius, the polar radius of ellipsoidal graphite particles has more sig- nificant influence on the characteristics of electrode microstructure.

关键词： Lithium-ion battery Graphite anode Microstructure reconstruction Simulated annealingmethod Ellipsoid particles

An Experimental Study on the Performance of a Stainless Steel-Water Loop Heat Pipe under Natural Cooling Condition

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Journal of Thermal Science 2014年第1期23卷 91-95页

作者： WANG Yiwei CEN Jiwen jiang fangming ZHU Xiong Laboratory of Advanced Energy Systems CAS Key Laboratory of Renewable EnergyGuangzhou Institute of Energy ConversionChinese Academy of Sciences (CAS) Qingyuan Resource Development Co.Ltd of China National Electric Power Corporation

Aiming to improve the thermal characteristics of modern electronics, we experimentally study the performance of a stainless steel/water loop heat pipe(LHP) under natural cooling condition. The LHP heat transfer performance, including start-up performance, temperature oscillation and total thermal resistance at different heat loads and with different incline angles have been investigated systematically. Experimental results show that at an optimal heat load(i.e. 60 W) and with the LHP being inclined 60 to the horizontal plane, the total thermal resistance is lowered to be ~0.24 K/W, and the temperature of evaporator could be controlled steadily at around 90 C.

关键词： Loop heat pipe cooling of electronics heat dissipation thermal resistance

A pore-scale smoothed particle hydrodynamics model for lithiumion batteries

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Chinese Science Bulletin 2014年第23期59卷 2793-2810页

作者： Jianbang Zeng fangming jiang Zhi Chen Laboratory of Advanced Energy Systems CAS Key Laboratory of Renewable EnergyGuangzhou Institute of Energy ConversionChinese Academy of Sciences Dongguan Amperex Technology Limited

A mesoscopic pore-scale model of multi-disciplinary processes coupled with electrochemical reactions in lithium-ion batteries is established via a relatively novel numerical method—smoothed particle hydrodynamics(SPH)*** model is based on mesoscopic treatment to the electrode(including separator)micro-pore structures and solves a group of inter-coupled SPH equations,including charge(ion in electrolyte phase and electron in solid phase),species(Li?in electrolyte phase and lithium in solid active materials),and energy conservation *** parameters,*** physicochemical properties are location-dependent,directly associated with the local component of the *** electrochemical reactions are prescribed to occur exactly at the interface of solid active materials and *** to isothermal discharge processes of a battery of 2-dimensional idealized micro-pore structure in electrodes and separator preliminarily corroborate the reasonability and capability of the developed SPH model.

关键词：流体动力学模型锂离子电池粒子电化学反应平滑能量守恒方程物理化学性质微孔结构

A numerical study of non-Darcy flow in EGS heat reservoirs during heat extraction

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Frontiers in Energy 2019年第3期13卷 439-449页

作者： Wenjiong CAO Wenbo HUANG Guoling WEI Yunlong JIN fangming jiang Laboratory of Advanced Energy Systems Guangdong Key Laboratory of New and Renewable Energy Research and DevelopmentCAS Key Laboratory of Renewable EnergyGuangzhou Institute of Energy ConversionChinese Academy of SciencesGuangzhou 510640China Guangdong Hydrogeology Battalion Guangzhou 510510China

Underground non-Darcy fluid flow has been observed and investigated for decades in the petroleum industry. It is deduced by analogy that the fluid flow in enhanced geothermal system (EGS) heat reservoirs may also be in the non-Darcy regime under some conditions. In this paper, a transient 3D model was presented, taking into consideration the non-Darcy fluid flow in EGS heat reservoirs, to simulate the EGS long-term heat extraction process. Then, the non-Darcy flow behavior in water- and supercritical CO2 (SCCO2)-based EGSs was simulated and discussed. It is found that non-Darcy effects decrease the mass flow rate of the fluid injected and reduce the heat extraction rate of EGS as a flow resistance in addition to the Darcy resistance which is imposed to the seepage flow in EGS heat reservoirs. Compared with the water-EGS, the SCCO2-EGS are more prone to experiencing much stronger non-Darcy flow due to the much larger mobility of the SCCO2. The non-Darcy flow in SCCO2- EGSs may thus greatly reduce their heat extraction performance. Further, a criterion was analyzed and proposed to judge the onset of the non-Darcy flow in EGS heat reservoirs. The fluid flow rate and the initial thermal state of the reservoir were taken and the characteristic Forchheimer number of an EGS was calculated. If the calculated Forchheimer number is larger than 0.2, the fluid flow in EGS heat reservoirs experiences non-negligible non-Darcy flow characteristic.

关键词： enhanced geothermal system non-Darcy flow heat extraction Reynolds number Forchheimer number